Nucleotide degradation of sodium acetate and potassium sorbate dip treated and vacuum packed Black Pomfret (Parastromateus niger) and Pearlspot (Etroplus suratensis) during chill storage

Quality changes of vacuum packed Black Pomfret (Parastromateus niger) and Pearlspot (Etroplus suratensis) treated with sodium acetate and potassium sorbate, respectively, and subsequently stored in vacuum packs in ice during chill storage were evaluated by measuring the volatile base nitrogen values, K-values and sensory parameters. The effects of sodium acetate (2% w/v) and potassium sorbate (2% w/v) dip treatments on vacuum packed Black Pomfret and Pearlspot were also examined. Total volatile base nitrogen values were found to increase slowly with time, whereas the K-values were found to increase linearly with time in samples of both the species and exceeded the acceptability limit on the day of sensory rejection. The K-values, representing the ratio between the sum of inosine and hypoxanthine to the sum of all other ATP breakdown products, was found to be a more reliable method for estimation of the quality of fresh/preserved fish. Sodium acetate/potassium sorbate dip treated and vacuum packed Black Pomfret and Pearlspot exhibited lower K-values compared to untreated samples. Treated vacuum packed samples of Black Pomfret were found to be in good and acceptable condition up to 16 days whereas treated vacuum packed samples of pearlspot remained in good condition up to 15 days compared to vacuum packed and air packed samples which were acceptable only up to 10 and 8 days, respectively. The sensory characteristics correlated well with the K-values for both the species. (c) 2006 Elsevier Ltd. All rights reserved.